Device on cutting facilities for packing machines

ABSTRACT

A gang-slitting machine, particularly for accurately slitting web-like sheets in which a plurality of rows of bags or packages have been preformed, to produce rolls of the bags or packages, comprising: disc knives securingly mounted on a driven shaft; backing means in the form of a guide disc for every disc knife; and two retaining discs for each knife, the retaining discs being of a smaller diameter than each disc knife and disposed one on either side thereof, whereby the slit strips each containing one row of bags or packages are pressed between each retaining disc and its associated guide disc and are guided so that the slitting is done only on the seams and not incorrectly beyond.

United States Patent Kreuschmer [151 3,668,965 [451 June 13, 1972 [54] DEVICE ON CUTTING FACILITIES FOR PACKING MACHINES 21 Appl. No.: 18,162

1,825,223 9/1931 Deck ..83/435X FOREIGN PATENTS 0R APPLICATIONS 175,103 9/[906 Germany ..83/435 Primary Examiner-Andrew R. J uhasz AttorneyHolman & Stern [57] ABSTRACT A gang-slitting machine, particularly for accurately slitting web-like sheets in which a plurality of rows of bags or packages have been preformed, to produce rolls of the bags or packages, comprising: disc knives securingly mounted on a driven shaft; backing means in the form of a guide disc for every disc knife; and two retaining discs for each knife, the retaining discs being of a smaller diameter than each disc knife and disposed one on either side thereof, whereby the slit strips each containing one row of bags or packages are pressed between each retaining disc and its associated guide disc and are guided so that the slitting is done only on the seams and not incorrectly beyond.

5 Claims, 4 Drawing Figures 56] References Cited UNITED STATES PATENTS 2,000,175 5/1935 Johnstoneetal. ..83/476 474,822 5/1892 Foote ....83/476 898,259 9/l908 Preston ..83/476 2 a 14 1 n I I DEVICE ON CUTTING FACILITIES FOR PACKING MACHINES The invention relates to a device relating to cutting facilities for gang slitting machines designed for the manufacture of packing bags or the like.

Cutting facilities are known which consist in the main of one or several rotating disc knivesand which serve to sub-divide a web of foil having ready-made packets into a large number of rows of ready-made packets and in such a manner that strips are formed, each of which exhibits one row of packets. The web of foil is thus divided in the direction of feed.

During the cutting process the web of foil with the readymade packets is supported by special, driven guides and is guided for example over disks. These disks operate in conjunction with the rotating knives and in such a manner that the knife engages in cutouts in the rotating disks so that assurance is given that the web of foil will positively be split up.

In the range of the cutting facility the web of foil is supported solely by the above-mentioned disks or the like, but not in the range of the packed goods. This is done so as to ensure that the web of foil will run securely on the guide or disk, a factor which is in turn required to ensure an accurate cutting process.

When the rotating knives now divide the web of foil into individual strips, the latter rest solely with their edges on the guides, i.e. the disks, and the result of this is that the strips run to one side, a fact which in turn has a disadvantageous effect on the guidance of the web of foil still to be cut. in particular, there is a danger that the cut will not always be properly made outside the range of the sealing seams, thus entailing that the sealing seams and hence the tightness of the packet will be impaired.

The problem cannot be solved by supporting the row of packets in the range of the packed contents. In many cases the packets are not all of the same height with the result that it is not possible to support them securely and uniformly. If the packets were supported, this would mean that they would no longer rest securely on the guides or disks in the range of the knives.

The object of the invention is to create with simple means a device on such cutting facilities, which device reliably prevents the web of foil cut into strips from running to one side.

The invention is based on a device on cutting facilities for machines designed for the manufacture of packing bags or the like, a cutting facility which comprises at least one rotating knife which divides a web of foil with several rows of readymade packets into strips, in particular with one row, the web of foil being led over driven guides, in particular disks, one of which is allocated to each rotating knife and which support the web of foil during the cutting process. The device according to the invention is characterized by the fact that the shaft of the rotating knives includes next to the knives freely rotatable retaining disks whose diameter is smaller than that of the knives; the retaining disks can be rotated on the knife shaft independently of the knives and press with their circumference the web of foil against the driven guide discs and their peripheral speed corresponds to the feed speed of the web of foil.

The invention thus proposes additional retaining means in the range of the knives, these retaining means being designed as freely rotatable disks which are arranged in particular in pairs on both sides of each knife. These retaining disks press the web of foil against the guide, i.e. against the disk which may be below the web of foil, and thus support the web of foil and also hold the edges of the cut strips firmly. Even if the web of the slit foil is pulled to one side, this cannot alter the position of the web of foil in the cutting range.

The retaining disks do not require a special drive system. They are freely rotatable and are driven simply by being moved by the web offoil.

it has been found that the web of foil is held securely when the retaining disks are cylindrical rings. [t is advisable to make the retaining disks flexible, for example by using the appropriate material or also by employing certain designs such as a conical or toroidally wave-shaped form, two designs which have already proved reliable.

lt is known to provide the disks with cutouts in which the outer circumference of the knives engages. in the invention it is advisable to match the distance between the two disks on either side of a knife to the width of this cutout.

A few embodiments of the invention are represented schematically in the drawings in which:

FIG. 1 a schematic side view of a section of a slitting machine embodying the invention,

FIG. 2 a section through a slitting machine incorporating a device according to the invention, and i FIG. 3 and 4 sectional representations of details of guide discs the invention in difierent forms.

The device according to the invention on cutting facilities can also be used for example when it is a question of cutting a web of foil 4 which consists of a large number of rows of ready-made packets disposed side by side into individual strips at the end of the machine 9 (cf. FIG. 1). in FIG. 1 it has been assumed that the end of the machine 9 exhibits the guide disk 5 over which the web of foil is led in the direction of the arrow 10. The knives 2 designed to divide the web of foil into strips is arranged in the range of the disk 5. The divided strips drop into the collecting container 1 l.

Naturally the invention can also be employed when the divided strips are subjected to a further process on the same machine, for example when they are divided into individual packets.

FIG. 2 shows that the web of foil 4 comprises at least 3 adjacent rows 12 of ready-made packets. Between every two rows 12 there are the guide disks 5 which are securingly mounted on a common shaft 13. The manner in which the shaft 13 is driven in not represented in greater detail. The circumference of the disks 5 are provided with cutouts 7 in which the knives 2 engage.

The knives 2 are securingly mounted on the rotating knife shaft 1. They are mounted by means of sleeves 17 which serve to brace the individual knives 2 firmly on the shaft 1.

Diametrically outside the range of the sleeves 17 the shaft 1 bears the bushes 14 which are held in a rotatable position by the bearings [5 so that the shaft 1 can be rotated in the reverse direction independently of the bushes 14.

The retaining disks 3 are advantageously mounted on the bushes 14. The peripheral surface 6 of the retaining disks 3 presses the web of foil 4 against the circumference of the disks 5.

It is obvious that in the case of this design the retaining disks 3 can assume a peripheral speed which corresponds to the peripheral speed of the disks 5 owing to the feed speed of the web of foil 4. In contrast, the rotational speed of the knives 2 is much higher.

Slightly conical-shaped retaining disks 3 are shown in the embodiment in FIG. 2. FIG. 3 shows a retaining disk which exhibits a toroidal wave-shape so as to improve the radial elasticity. FIG. 4 shows a further variant of the retaining disc of the invention.

Whereas the embodiment according to FIGS. 3 and 4 the retaining disks are held on the bush 14 by their own elasticity, the embodiment in FIG. 2 shows a mounting ring 16 which serves to secure the retaining discs on the bush l4.

lclaim:

l. A slitting machine for slitting a web of foil material, comprising: at least one disc knife securingly mounted on a first rotatable shaft; means to rotate the shaft at a predetermined speed; at least one guide disc disposed with its circumference in close proximity with a circumferential cutting edge of said disc knife and securingly mounted on a second shaft having its axis parallel to the axis of said first shaft; and two freely rotatable retaining discs of diameter less than the disc'knife diameter and mounted one on either side of said disc knife, means journalling said retaining discs for free rotation about said first 4. A slitting machine as claimed in claim 1 in which each of the retaining discs is toroidally wave shaped.

5. A slitting machine as claimed in claim 1 in which said guide-disc includes an annular peripheral recess in which the cutting edge of a corresponding disc-knife engages and wherein an axial width of said recess is equal to a spacing between two associated retaining discs.

* U O l I 

1. A slitting machine for slitting a web of foil material, comprising: at least one disc knife securingly mounted on a first rotatable shaft; means to rotate the shaft at a predetermined speed; at least one guide disc disposed with its circumference in close proximity with a circumferential cutting edge of said disc knife and securingly mounted on a second shaft having its axis parallel to the axis of said first shaft; and two freely rotatable retaining discs of diameter less than the disc-knife diameter and mounted one on either side of said disc knife, means journalling said retaining discs for free rotation about said first rotatable shaft, whereby the web of foil while being slit is continually and guidingly pressed adjacent each slit at the region of slitting, in between the peripheries of a respective guide disc and a retaining disc.
 2. A slitting machine as claimed in claim 1 wherein the retaining discs are resiliently flexible radially.
 3. A slitting machine as claimed in claim 1 in which each of the retaining discs includes a conical shaped region.
 4. A slitting machine as claimed in claim 1 in which each of the retaining discs is toroidally wave shaped.
 5. A slitting machine as claimed in claim 1 in which said guide-disc includes an annular peripheral recess in which the cutting edge of a corresponding disc-knife engages and wherein an axial width of said recess is equal to a spacing between two associated retaining discs. 